A unit of the type mentioned at the outset is already known in which a tactile output is arranged on a stage raised behind the input keyboard. Thereby in feeling the output lines, the hand feeling for this must be held stretched far forward and free above the input keyboard which leads to more rapid fatiguing of the operator.
In another unit of the type mentioned at the outset, the read-out panel comprising two tactile read-out lines and the control keyboard are accommodated on a case separate from the input keyboard, in which case the read-out panel and the input keyboard lie in different planes. This yields the disadvantage that there is an upward or downward step between the read-out panel and the input keyboard, and the input keyboard has no fixed spatial position relative to the read-out panel. This makes orientation between the read-out panel and the input keyboard difficult for the vision impaired. The same holds true to a limited degree for the orientation between the readout panel and the control keyboard.